Refractory and method of making the same



Patented May 27, 1930 warren STATES PATENT OFFICE HAROLD C. HARRISON, OFCOLUMBUS, OHIO, ASSIGNOR TO MOLANAHAN-WATKINS 00.,

OF.HOLLIDAYSIBURG, PENNSYLVANIA, A PARTNERSHIP REFRACTORY AND METHOD OFMAKING THE SAME No Drawing.

This invention relates to ceramic refractory materials and has among itsprincipal objects the provision of a refractory material of the ceramictype having more desirable properties under the conditions of actual usethan similar materials hitherto known.

Among the many serious defects of ceramic refractories which were knownprior to the present invention, perhaps the most obj ectionable aretheir tendency to soften or spall or to fail under the severe conditionsto which they are normally subjected in use such as exposure to hightemperatures, sudden or rapid fluctuations in temperature, subjection tovarious mechanical stresses or loads at high temperature ranges, as wellas their tendency to flux to an objectionable degree with variousmaterials with which they are necessarily or normally brought intocontact.

invention is particularly adapted to uses where strongly fluxingmaterials are excluded as in high temperature ceramic kilns, combustionchambers of high temperature boiler installations, and the like, it isalso applicable generally where the older refractories have givenunsatisfactory results because of their above mentioned defects.

The following example of my invention is given by way of illustratingthe preferred form thereof, it being understood that the scope of myinvention is in no wise limited by the particular conditions and meansemployed therein.

Example-In the practice of my invention 1 may take 45 parts by weight ofa cyanite concentrate comminuted to a fineness which passes a 28meshTyles standard screen, but which is retained on a 48 mesh screen ofthe same standard; 23 parts by weight of a cyanite concentrate of afineness to pass a200 Application filed December 22, 1924. Serial No.757,542.

mesh screen of the same standard and 32 parts by weight of a bau'xiticclay as a high aluminous bond of the type now commonly known to thoseskilled in the art as Georgia bauxitic clay. I have obtained goodresults with a cyanite concentrate which upon analysis showed thefollowing composition:

Per cent S10 38.54 A1208 F '-58.62 F8 0. 1.54 TiO 0.64 P 0 0.02 GaO v r0.10 MgO 0.24 K 0 0.00 NagO l Loss of ignition (ove'r meeker type gasburner) 0.27

This cyanite deformsat about cone 36. The bauxitic clay in the presentexample has approximately the following composition:

Per cent SiO 14.42 A1 0 56.23 Fe O 0.96 TiO 2:34 P205 (3210 0.31 MgQ0.12 K 0 0.00 Na O 0.00 Sulphur 0.06 Moisture at 105 C 1--. 0.46

Loss of. ignition (over meeker burner); 25.41

This clay deforms at about cone 39. The clay is wet ground in a pebblemill toa creamy slip, with a water factor of about 2 (2.5) and' is addedin this condition to the cyanite concentrate until completely mixedtherewith. The resulting mixture is then de-watered by placing it upon aplaster of Paris absorption block covered with musline cloth to preventcontamination with calcium compounds until the watered content isreduced to between 5% and 15% or until the resulting mass will readilyform by dry pressing. The materialis then dry pressed at a pressure ofabout 600 lbs. per sq. in. It

is then removed'from the press and dried brick is then fired to cone inabout 32. hours in a natural gas fired'kiln having a volume of about 9cubic feet.

As previously-mentioned, I may vary the} particular proportions andother factors in the preceding example without departing from the scopeof my invention. Thus, I may use a cyanite concentrate in the raw batchcontaining anything above 85% cyanite mineral (i. e. a concentrateofcyanite mineral analyzing above about 53% aluminum) Also, for the hi haluminous bond, I may use in place of the eorgia beauxitic clay a clayof the diaspore type or any other bonding material showing above about65% A1 0 on a calcined basis and having a-plasticity of about that ofthe Georgia bauxitic clay or higher. I

The cyanite concentrate or cyanite mineral may be substituted in theabove example bg any mineral of similarcomposition and c aracterbelonging to the :ganite group of mineral, it being understo that theterm cyanite group and similar expressions as used herein includesbesides cyanite itself the minerals sillimanite, and alusite and thevariations of all threeof these specific minerals, provided thatinthe'group of minerals specified, the proportion ofcoinbined alkali andalkalin earth oxides or any group of these oxides is not in excess ofabout 1%.

Also, I may decrease the proportionof the 'cyanite mineral concentratewithin the range of about 2%, adjusting the proportions of the otherconstituents accordingly. The proportion of the-cyanite concentrate maybe increased up to 100%, depending upon the result desired. p

- The degree of fineness of the cyanite and the relative proportions ofthe difierent grades of fineness thereof, the conditions of grinding,de-watering and drying the batch, as well as the condition of firing thedried mass, may be varied according to the results desired, all inaccordance with practices and methods generally known to those skilledin the ceramic art.

In preparing the raw batch, I prefer to commute the mineral to a degreeof fineness such that no appreciable proportion of the mineral componentof the raw batch will not pass a' 10 mesh sieve of the Tyler standard.'. In other words, the maximum particle size should correspond inthe main to material passing through the 10 mesh sieve.

The finished fired product of the present invention is characterizedbroadly not only by its content in mineral of the cyanite group tions toform the raw batch.

. eral of the cyam'te group and its high aluminous bondin material, butalso by its very high refractoriness which is equal to-andin manyinstances is superior to that of'silica brick- It is further 0aracterized by possessing a load carrying capacity approaching that ofsilica brickand a resistance -to spalling superior to that of silicabrick.

Iclaim: A

1. The method of producing a refractory ceramicproduct which comprisesfirst preparing a raw batch containing more than 50% by weight of amineral belonging to the cyanite group and subsequently dry pressing thebatch into the desired shape and firing the dry pressed article thusobtained. I

2. In the method set' forth in claim '1, comminuting a portion of themineral to one degree of fineness and comminuting another portion of themineral to a different degree of fineness and subsequently mixing thetwo por- 3. In the method set forth in claim 1, comminuting the mineralto a fineness such that no substantial proportion has anaverage-particle size greater t an that'which will pass a 10 mesh sieveofthe Tyler standard type.

4. A fired ceramic refractory material comprisin more than 50% by weightof a mineral o the cyanite grou and a high aluminous bond, thecomposition being substantially free from alkali or alkaline earthfluxes and the composition being characterized further by arefractorinesssubstantially as high as that of silica brick, anon-vitreous structure and a porosity substantially greater tha that oforcelain.

5. A red ceramic refractory material comprising more than 50% byweightof a minand a high aluminous bond, the composltion being substan-I tially free from alkall or alkaline earth fluxes and the compositionbeing characterized furtherby a refractoriness substantially as high asthat of'silica'brick and a load carrying capacity approachin that ofsilica brick and a resistance to spalling greater than that of silicabrick, a non-vitreous structure and a porosity substantially greaterthan that of porcelain. 1 r

6; The method of producing a refractory cermicproduct of thenon-vitreous type having a porosity substantially greater than porcelainwhich comprises first preparing a raw batch, substantially free fromalkali or eral'cyanite, forming the batch into the desired shape andsubsequently, firingv the formed material thus obtained.

7. The method of producing a refractory ceramic product of thenon-vitreous type having a porosity substantially greater than porcelainwhich comprises first preparing a raw batch, substantiallyfree fromalkali or alkaline earth fluxes and containing a conalkaline earthfluxes and containing the min-' r centrate ofthe mineral cyanite, thesaid concentrate possessing a degree of refractoriness corresponding todeformation at about cone 36, formingmthe raw batch into the desiredshape and ing the formed article thus oh- I tained.

8. A fired ceramic refractory material of the non-vitreous type having aporosity substantially greater than porcelain comprising fired mineralcyanite the material being substantially free from alkali or alkalineearth material being 9. -A fired ceramic refractory material of thenon-vitreous type having a porosity substantially greater t an porcelaincomprising a fired concentrate of the mineral cyanite, the substantiallyfree from alkali or alkaline earth fluxes and the said concentratepossessing a degree of refractoriness corresponding to deformation atabout cone 36. I

In testimon whereof I aflix my signature.

' OLD C. HARRISON.

